Best nut height for fast action on P bass

Hello all,
You guys have always come up with some great advice on setups. I had a question for all you p bass users out there. What is the best height for the nut (on the bass that is)? I like my action pretty low, but I also drop tune to low as C# on my E string. Meaning, it can't be so low it will buzz. I've done some searching on the technique of filing the nut, but I was wondering on the exact specifications. I'm pretty familiar with setups (thanks to all of you TB'ers out there)
Thanks!

Um, I'm not sure how to answer this. I have a P-Bass, it has insanely low action, but do you want like actual dimentions of the slots? If so, bear in mind that different string gauges will affect the cut into the nut.

I guess so (referring to the exact dimensions). I'm just a little nervous on filing the nut. I don't want to go too low. I'm good at setting up my bass, but I haven't done this before. I don't want to take it into a luthier because I'm very picky. Any suggestions?

Yeah, I've done the entire set up (truss rod, bridge, pickup height, intonate), but it still is a little high. I'm going to have to file my nut. Thanks for the tips man. I really appreciate it. Hope all goes well!